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4.2 Condensation Chamber
The test is carried out according to ISO 6270.
This test is specially designed to evaluate coatings for the protection of steel in environments with high humidity and condensation, such as water ballast tanks. The test gives information regarding the water permeability of a coating system. The condensation chamber functions as follows:
A covered plastic chamber has fresh water of 40℃ in the bottom. The test panels are placed on the top of the chamber at an angle of 15°to the horizontal with the back side to the room with temperature 23 ± 2℃, Water evaporating from the bottom of the chamber condenses under the panels on the coating to be tested.
The size of a panel is 150mm x 150mm x 5mm for two test panels per paint system to be installed.
Figure 5: Condensation Chamber
4.3 Exposure Times
The exposure time is 180 days for all types of systems.
5 Evaluation and Classification of Hard Coatings
5.1 Evaluation of Blisters and Rust
At intervals during the exposure and once the test has been completed, the coatings are evaluated regarding degree of blistering and rusting according to the following standard:
ISO 4628: Paint and varnishes - Evaluation of degradation of paint coatings - Designation of intensity, quantity and size of common types and defect.
Part 1: General principles and rating schemes.
Part 2: Designation of degree of blistering.
Part 3: Designation of degree of rusting.
5.2 Physical Testing
Before exposure one small panel (15 x 15cm) and one large (20 x 40cm) are tested for pinholes with a low voltage pinhole detector at 90 volt. The number of pinholes is recorded.
After the tests have been completed the adhesion is tested according to ISO 4624: Paints and varnishes - Pull-off test for adhesion. Test plates to have a minimum thickness of 5mm.
The effect of the waves, the heat and the temperature gradients are visually evaluated.
Undercutting from a scribed defect is evaluated and recorded (on wave tank top heated, side cooled and side uncooled panels).
Flexibility is tested according to a modification of ASTM D4145: Standard Test Method for Coating Flexibility of Prepainted Sheet. From the top panel of the wave tank and an unexposed panel 3 pieces of size 5 x 15cm are cut up. The pieces are bent at 5, 20 and 40mm in 180°and the result is reported as minimum diameter of no paint fracture. If paint fracture is seen even at 40mm diameter, degree of bend at fracture is reported.
Pull-off and flexibility tests are carried out at a minimum of two weeks after exposure.
For the panel with anode, the current demand is calculated and the effect of the cathodic protection (disbonding/blistering) is visually evaluated.
5.3 Classification of Hard Coatings
The classification is mainly based on the density of blisters and the area rusted according to the following system:
Table 1: Classification of Hard Coatings
(Blisters and Rust According to ISO 4628/2 and ISO 4628/3)
| HARD COATINGS |
Area blistered |
Area Rusted |
| Class B-1 |
No blisters |
Ri 0 (0%) |
| Class B-2 |
Density 1 - 2 either on the cold wall wave tank panel or in the condensation chamber panels |
Ri 1 (0.05%) |
| Class B-3 |
Density 1 - 2 on the cold wall wave tank panel and in the condensation chamber panels |
Ri 2 (0.5%) |
| Class B-4 |
Density 3 - 4 either on the cold wall wave tank panel or in the condensation chamber panels |
Ri 3 (1%) |
| Class B-5 |
Density 3 - 4 on the cold wall wave tank panel and in the condensation chamber panels |
Ri 4 (8%) |
| Class B-6 |
Density 4 - 5 |
Ri 5 (40/50%) |
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To be acceptable for use in ship's ballast tanks the coating system must achieve the B-1 classification.
Figure 1: Paint Application Form
Figure 2: Product Data Sheet
執筆担当者
宮本 武 吉田 公一 高田 篤志
岡 正義 丹羽 敏男 原田 晋
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